Field of the Invention
The present invention relates to a storage medium storing a video game program and, more particularly, to a storage medium storing a video game program for playing a video game using a controller.
Description of the Background Art
In the prior art, Japanese Laid-Open Patent Publication No. 11-305935 (hereinafter “Patent Document 1”), for example, discloses a position detection system for taking an image of an infrared light source and analyzing the obtained image to determine a gunsight position.
As an example of a position detection system, Patent Document 1 discloses a shooter video game in which the player shoots targets by using, as a game controller, a gun-shaped controller provided with an image capturing device. Four infrared light sources are provided, as imaging targets, each at a corner of a cathode-ray tube, and an image thereof is taken by the image capturing device. The position on the cathode-ray tube being pointed at by the gun-shaped controller is detected based on the positions of the imaging targets on the obtained image. A virtual shooter game is played by using the position being pointed at by the gun-shaped controller as the gunsight position. As stated in Paragraph 21 of Patent Document 1, in a case where the distance between the image capturing device and the target (marker) can be changed freely, the gunsight position can be detected accurately if the image capturing device has a controllable zoom function and if the zoom function is controlled so that the marker on the obtained image always has an optimal size.
However, there is no such concept in the prior art that the distance between the game controller and the imaging target is used directly as a control input. For example, in the position detection system disclosed in Patent Document 1, the distance between the image capturing device and the marker is used only for making corrections, and variations in the distance rather hinder an accurate control input. If the movement in the distance direction between the game controller and the imaging target is used as a control input, the range over which the player can move the game controller in the distance direction will be quite large, whereby the distance input range and the distance input variation will be significant. Therefore, it is difficult in the prior art to use the distance itself as a control input. Moreover, where the player makes the control input vary depending on the situation, thereby varying the distance value. With those problems as set forth above, there is no such concept in conventional control input methods that the distance between the game controller and the imaging target is used directly as a control input.